For a search system that searches for a document containing links, such a Web page, a technique for determining the display order of search results has been used (refer to, e.g., Patent Document 1, Patent Document 2, Non-Patent Document 1, and Non-Patent Document 2). A technique disclosed in Patent Document 1 determines the importance of each document based only on link relationship among documents to be searched for and displays search results in the descending order in terms of the importance.    Patent Document 1: U.S. Pat. No. 6,285,999    Patent Document 2: U.S. Patent Application Publication No. 2005/0071741    Non-Patent Document 1: “The PageRank Citation Ranking: Bringing Order to the Web”: Lawrence Page, Sergey Brin, Rajeev Motwani, Terry Winograd (Jan. 29, 1998)    Non-Patent Document 2: “Efficient Computation of PageRank”: Taher H. Haveliwala (Oct. 18, 1999)
However, the technique disclosed in Patent Document 1 can calculate the importance of the document to be searched for based only on the link relationship among the documents to be searched due to a large limitation imposed by the importance calculation.
Further, there are available some methods for calculating the importance considering influence of a plurality of types of parameters. A technique disclosed in Patent Document 2 calculates the importance based on the link relationship and then corrects the importance based on another parameter. However, the information calculated based on the link relationship is lost by the correction made based on the another parameter. Further, the technique disclosed in Patent Document 2 does not describe a concrete method for taking the influence of a plurality of types of parameters into consideration.
Although there can be considered a method in which weighting is given to a plurality of obtained importance degrees that have been calculated for each parameter, this method entails a problem that, since the importance calculation involving time-consuming iterative calculations is performed for each parameter, calculation amount becomes enormous.